Audible - Audible is the world’s largest provider of premium audiobooks and spoken word content.
TunesKit iBook Copy for Mac - Easily remove DRM protection from Apple iBooks and copy DRM protected iBooks to DRM free ePub files.
LibriVox - free public domain audiobooks
Kingshiper MP3 Converter - Kingshiper MP3 Converter is a reliable and easy-to-use tool to convert your music files into MP3 format in seconds.
DigitalBook.io - Free audio books and eBooks. Search, browse, listen, read and download over 100,000 free audio books and eBooks.
OpenAudible - OpenAudible Project Page